A lithium-ion secondary battery has been widely used as a power source of, e.g., a notebook-sized personal computer, a video camera, a cellular phone, or an electric automobile. As such a lithium-ion secondary battery, a battery in which the periphery thereof is covered with a case has been used. As a case packaging material, a packaging material in which a thermoplastic resin non-oriented film and an aluminum foil are bonded via a thermal adhesive resin is known. As a production method of such a packaging material, a method in which a polyolefin film and a modified polyolefin film are co-extruded between a thermoplastic resin non-oriented film and an aluminum foil which are being supplied and then they are integrally bonded (see Patent Document 1) and a method in which after applying organozol having a solid content of acid modified polyolefin onto an aluminum foil, the organozol is dried to thereby form an adhesive film, and then a polyolefin film and the adhesive film are pressure-bonded (see Patent Document 2) are known.
Patent Document 1: Japanese Unexamined Laid-open Patent Publication No. JP 2002-96419, A (claim 1, paragraph [0017])
Patent Document 2: Japanese Unexamined Laid-open Patent Publication No. JP 2000-67823, A (claim 1)